Photochemical polymerization of oligothiophenes and dithienothiophenes were investigated. Photo-irradiation to solutions containing a series of the thiophene derivatives acid appropriate electron acceptor gave alpha-linked polymers having molecular weight of about 10(4) (vs. PSt.). In the case of oligothiophenes, cation radicals of the monomers were efficiently generated through the photoinduced electron transfer from the triplet excited state to the electron acceptor. Then the successive coupling reaction resulted in a formation of polymeric products. On the other hand, photoinduced electron transfer from singlet excited state of dithienothiophenes to electron acceptor was suggested as a generation mechanism of their cation radicals.
